An Experiment in ATOMIC STRUCTURE verifying  Einstein's theory of mass and energy, as an undergraduate student.

E=MC2
 
Repeating the famous Cockcroft and Walton, 1932 transmutation experiment with guidance from Lord Rutherford's, using  artificially produced projectiles. (i.e. a  atom smashing)

For my Senior under graduate  science project, could I

  with a limited resources, a modest budget and with a only senior level education in university with no graduate school,
 repeat this experiment?

by Jim Morris 1954

    781 245 2897     k1ugm@comcast.net

Incentive? Why take on  a project of this magnitude just for a one  semester hour senior course credit?

Possibly because I had a strong love physics and  and  an deep infatuation with beautiful Marie Curie. aT 87,, I still have her picture up on my office wall.

 Most important it would not have possible with out  the patience and understanding of the head of the small physics department in a equally small  Lutheran sponsored University in the northeastern part of Indiana. I also was working full time as a telegraph operator with a family of three children.

Most important I did not have the good sense not to do it

The beast!

 

 

Lord Rutherford's  "Nuclear physics?

Copied from Wikipedia

Rutherford's research, and work done under him as laboratory director, established the nuclear structure of the atom and the essential nature of radioactive decay as a nuclear process. Rutherford's team, using natural alpha particles, demonstrated induced nuclear transmutation, and later, using protons from an accelerator, demonstrated artificially-induced nuclear reactions and transmutation. He is known as the father of nuclear physics. Rutherford died too early to see Leó Szilárd's idea of controlled nuclear chain reactions come into being. However, a speech of Rutherford's about his artificially-induced transmutation in lithium, printed in 12 September 1933 London paper The Times, was reported by Szilárd to have been his inspiration for thinking of the possibility of a controlled energy-producing nuclear chain reaction. Szilard had this idea while walking in London, on the same day.

Rutherford's speech touched on the 1932 work of his students John Cockcroft and Ernest Walton in "splitting" lithium into alpha particles by bombardment with protons from a particle accelerator they had constructed. Rutherford realized that the energy released from the split lithium atoms was enormous, but he also realized that the energy needed for the accelerator, and its essential inefficiency in splitting atoms in this fashion, made the project an impossibility as a practical source of energy (accelerator-induced fission of light elements remains too inefficient to be used in this way, even today). Rutherford's speech in part, read:

We might in these processes obtain very much more energy than the proton supplied, but on the average we could not expect to obtain energy in this way. It was a very poor and inefficient way of producing energy, and anyone who looked for a source of power in the transformation of the atoms was talking moonshine. But the subject was scientifically interesting because it gave insight into the atoms.[20]

 

Background of the original experiment. The artificial disintegration of the Lithium nucleus producing 8.58 + million volt alpha particles hitting them with 150,000 volt protons.

 In 1932   Cockroft and Walton, at the Cavendish Laboratory, Cambridge  employed a number of kenotrons.

 in series multiplying circuit, succeeded in producing high voltage to accelerate protons to energies of 100,000  to 700,000 electron-volts. (Kenotrons are vacuum rectifying hot cathode tubes of the diode type). Their power supply was very large and very expensive.

With this power supply they  bombarded lithium and produced the first transmutation by means of artificially produced projectiles (protons), as follows: They ionized hydrogen giving them protons which they shot at a Lithium target. with the high voltage power supply. The result was  8,530,000  electron volt alpha particles. The equation of the reaction is

{ 1H1 + 3Li7 }  --->  2He 4 + 2He4 + E.   equation (1) p435

The hydrogen nucleus (proton) combined with the lithium nucleus to produce two helium nuclei (alpha particles). These two helium nuclei are shot out in opposite directions with the great kinetic energy of  8.53 X 10 6 electron volts each See Fig. 1.

The reaction was an important test of Einstein's theory of mass and energy.

Figure (1) shows a drawing of a cloud chamber picture of three such pairs. This energy, less the initial kinetic energy of 150,000 ev of the proton, is represented in equation (1) by E. From the magnitude of the energies of the alphas, it is seen that the reaction is in the nature of an explosion.

The question of whence came this enormous energy exhibited by the alphas in the  transmutation of mass and energy. One of the conclusions from Einstein's theory of relativity was that mass should be changeable into energy or energy into mass according to the relation:

 E = mc2     

where
 m is the mass in question
 c is the velocity of light
E is the energy equivalent to mass m.

This prediction of the relativity theory is verified in a highly satisfactory way by the reaction of Eq. (2). Taking atomic masses in terms of eV of the mass of an oxygen atom as a unit, to which the name Dalton has been given, we have the following values: Writing these masses for the nuclei in Eq. (2), we have

 iH1 + 3L7 --->  2He4 + 2He4 + E gives 1.0075 + 7.0132 = 2(4.0011) + E

where E=0.0185

 Hence, if the laws of conservation of mass and of energy hold true, the energy E must equal 0.0185 Dalton.

It may be shown that

1 Dalton = 927 X 106 electron-volts.

Therefore

0.0185 Dalton = 0.0185 X 927 X 102 = 17.15 mev

The observed value of the energy of the two alphas in their experiment  was 17.06 mev. The calculated and experimental values are in excellent agreement and offer strong confirmation of theory. In the foregoing we have an example of the transformation of matter into energy.

 

 

 

FIG. (1). Transmutation of Lithium into Helium shown in a drawing of a cloud chamber event.

Ref.1, Physics by Frank L. Robeson Macmillan Co New York 1942

Ref, 2 Procedures in Experimental Physics by John Strong etal.1938-1956 Prentice- Hall, Inc.

Ref 3,  The Particles of Modern Physics by J.D. Stranathan 1943-1946 Blakiston Co. Philadelphis . Toronto p 435---

 

Repeating this experiment on a more modest scale.

The Experimental Apparatus developed and made by the author for this project

  1. A Van de Graff high voltage generator with a 5 micro amps ion beam current and  over 250,000 volts,
  2. The high voltage resistor for measuring ion current
  3.  subsidiary power supplies for charging the belt of the high voltage source
  4. A Glass  high vacuum system with pressures less than 1 *10-6 mm of Mercury
  5. A glass accelerator tube complete with ion source and targets
  6. Radiation detectors and their circuits,

    All of the equipment was built in the metal and glass shop of the university by the author. The critical material was donated from local business's.

Below are drawings of the critical components built for the project.


The pressure in the high vacuum side was less than 10 ^_6 mm Hg.


The ionization source was a 3 volt flash light bulb with the glass surrounding the filament removed.. Hydrogen was introduced into the accelerating tube  through the Palladium tube from the hydrogen flame that was heating it to a very dull red.

The voltage from the generator at 5 micro amps ion beam current was over 250,000 volts.

A home made Geiger counter.
The circuit for both radiation counters
Photographs of the finished apparatus with  a description of the  location of the components  assembled for the experiment.

The vacuum system is in the rack center left. The accelerating tube at a 60 degree angle coming out of the left side of the sphere. above that is the high voltage resistor. Glass rods  for turning on and adjusting the filament ionizer come out of the sphere each side of the accelerating tube.  The motor driving the belt was  1/3 horse power aircraft motor capable of 1900 rpm. The belt was wax treated craft paper.  A d.c. 30,000 volt 50 ma. power source was connected to the lower comb to stabilize the power to the accelerating tube. Both the phosphor  screen and the radiation detectors. indicated radiation at the target end of the tube.

 


A photograph of  the author and the head of the physics department checking

the high voltage supply and the accelerating

 tube.

A photo of myself and Dr .A. Thomas Head of the Physics & Math Dept. Valparaiso Un.

50 years of physics later, my wife a chemist working together helping people help scientist help the people toward a better life.

 Here I am making a electrostatic pickup comb for a electrostatic disk generator (see below) I am building
for the President James Madison  Foundation.





The disk generator is serving a useful purpose educating the public about the broad scope of the awareness

 our Presidents used to have.

 

Conclusion

As to the success of my  senior year undergraduate school project;

I did have some introductive experience, such as,  For my freshman and  sophomore years in chemistry I did, for free, many  experiments in liquid chromatography field  for one of  my chemistry instructor who had a government funded project. I was a real cheap labor source and loved it. I did all yes all  of the experiment in the lab manuals for each course I took including those in the  more complicate end of the books, usually untouched  by most students. I added to the my analytical chemical analysis courses  my own spectroscope and used it, without permission .I made improvements  in a the accuracy of the chemical balances. without permission. The instructors wondered at the sudden improvements  the class  lab scores.

 I had a lots of  experience in the physics laboratory  repairing all of the broken apparatus for the all lab experiments,  acting as a student lab assistance for a few semesters  for the freshman through senior  students. In my spare time I expanded  the  schools 3 meter  grating  spectroscope, photographic system, per request. etc. etc. it was a wonderful friendly experience if you did not mind working18 hours a day and bring my children to labs to play with the instrument that were working even after I fixed them..

The project took

  1. At least 240 hours shop work learning and practicing my skills in glass, metal,  and wiring

  2.  16 hours of lab work including trouble shooting.

  3. $15 out of pocket expenses the local industries were very helpful.

  4.  I was able to detect scintillations on a fluorescent screen and to get detection on the electric counters.. at voltage ranging from 75,000 to 350,000 volts across the accelerating tube.

  5. The transmutation was a function of the h. v. which depended on the beam current which was a  function of gas pressure and purity.

  6. The detection was erratic because of poor control of the hydrogen pressure in the tube, and ion blocking inside the accelerating  tube making it difficult to get quantitative data.

    One of the most important things learned, and most important, most unknown, was getting funding for the project. This  gave me very valuable experience for future senior work.

    Question was it all worth it.

    The project gave me more technical access to the teaching staff over a broader range of topics than taught both experimentally and theoretically I got the confidence of the teaching staff which helped me get more training than the average student, By far they made it work for me.

    With the help of the head of my  physics department. I got a position  at Illinois  Institute of Technology, I got a government contract doing research in the thermal radiation from a varieties of material. This allowed me to start publishing technical papers in replicable scientific journals, A necessary thing to stay in the field.